I HATE "diet" salad dressing..it just tastes gross to me. There is a brand I get called "litehouse" (I don't think it's promoted as "lite" but not sure) They have a bunch of varieties that have 2 sugars that are very yummy.
I'm one of those people who likes a lot of dressing, so I got some that ztrim stuff to make it go a little further for creamy dressings and I add a little olive oil or more vinegar or some white cooking wine to my "oily" dressings.
On a side note, there is a local company here that makes the most amazing salad dressing. My absolute favorite is "Creole Tomato" (it really doesn't taste much like tomotos, more like a mildly spicey super fantastic ranch) It has NO sugar in it at all. It comes refridgerated, so I'm sure it will be a bit pricey to have it shipped overnight, but as a treat I would think it would be worth the price.
http://www.cousinsproducts.com